Glass-forming ionic mixtures are materials relevant for, e. g., modern energy applications. Besides typical dynamics of a glass former, they often show structural inhomogeneities, affecting crucial properties like ionic conductivity. Two classes of these mixtures are in the focus of the present work: polymer electrolytes (PE) and ionic liquids (IL). The PE studied here show a maximum in conductivity measurements for intermediate salt concentrations, which are at the same time prone to microphase separation. Ionic liquids show increasingly heterogeneous local dynamics with increasing cation size, up to the point of cation-cluster formation in the liquid bulk. Here, these inhomogeneities were studied systematically by varying the salt concentration in PE, or tuning the cation size in IL, respectively. Using isotope-sensitive nuclear magnetic resonance spectroscopy (NMR), influences of these alterations on local and long-ranged dynamics were ascertained separately for each of the components (polymer, anions, cations). In the case of PE, local segmental dynamics could be accessed by field-cycling (FC) NMR for the first time. The inherent Rouse dynamics of the polymer chains is not altered on addition of lithium salts on a reduced time scale. Moreover, lithium ions in the salt are complexed to the polymer backbone in such a way that due to the resulting coupling of dynamics they imitate the Rouse modes of the chains. Intermediate PE mixtures show bimodal segmental relaxation resulting in two contributions to the respective susceptibility representations. The two processes were attributed to salt-rich and salt-depleted domains in these samples. For all mixtures, diffusive and local dynamics show the same temperature dependence. Thus, rotational and translational motions are coupled. This coupling even holds when correlating the lithium-ion migration and segmental reorientation of the polymer via the Stokes-Einstein-Debye (SED) relation. The SED-product D(Li) · τ(Pol) is constant for all studied temperatures. In the second part of the present work local relaxational processes of two IL were analyzed, both comprising the imidazole cation but different anions. For an IL containing TFSI-anions the size of the cation was varied systematically by stepwise increasing the length of an attached alkyl chain. In 1H and 19F FC experiments local cation and anion dynamics showed a similar slowdown with decreasing temperature, with only moderate differences between short an long alkyl chains. No signs of an aggregation of charge carriers were found. Additionally, 2H spin-lattice relaxation and stimulated-echo experiments gave valuable insights into the isotropic rotational motions of the cations. Structural relaxation predominantly takes place via small-angle jumps. The combination of 1H and 2H experiments yielded correlation times of cation reorientation over eleven decades in time. Accessing the molecular diffusive motion by applying static field gradient NMR, small diffusion coefficients of cations and anions can be probed. In combination with the correlation times ascertained beforehand the anions of all measured IL fullfill the SED relation in a wide temperature range. In contrast, a breakdown of the said relation is found for the cation data if the alkyl-chain length is increased to six or more carbon atoms. Contrary to the increase of the SED product for such a breakdown in other glass formers, here the product showed a decrease upon cooling. This unusual behaviour was attributed to cation aggregates forming a barrier to long-range diffusion, while not affecting the local rotational processes. To conclude, in this work diverse coupling mechanisms were found for both classes of ionic mixtures. In PE the complexation of lithium ions by the polymer backbone leads to a strong coupling of both dynamics, regardless of heterogeneous polymer motion in the samples with intermediate salt concentrations. In IL, translational and rotational motion of the cations decouple when structural inhomogeneities are increased. For both systems it was shown in detail how aforementioned structural effects and couplings on a molecular level result in complex microscopic and macroscopic dynamics. The understanding of these mechanisms is essential for designing new materials and optimizing attributes for specific applications.